Hitachi, Ltd.

Hitachi Information Control Systems, Inc.

Makoto Tachikawa

Noboru Azusawa

Toshihiko Matsuda

Takeshi Katoh

Tadashi Okamoto

Tadahiko Hashimoto

Junichi Hamano

Kuniyuki Igari

Akihiro Ohhashi

Hitoshi Saitoh

Tsutomu Omae

Tsutomu Ohmae

Toru Ishikawa

Ichirou Katsuyama

A process controlling method and apparatus which uses a flowchart language program and ladder programs with an intermediate register accessible using the same name by both the flowchart language program and the ladder programs. Each ladder program defines the operation of a machine, including an interlock condition of the machine operation. The flowchart language program defines an automatic operation flow which sequentially activates the ladder programs using the data in the intermediate register. This arrangement allows the flowchart language program to be separated from the ladder programs improving productivity, serviceability and security of the programs.

Apparatus and method for controlling a system process

A process controlling method uses a flowchart language program and ladder programs with an intermediate register to be accessible with the same name by both the flowchart language program and the ladder programs. Each ladder program defines the operation of a machine, including an interlock condition or the like of the machine operation. The flowchart language program defines an automatic operation flow which sequentially activates the ladder programs using the data in the intermediate register. This arrangement allows the flowchart language program to be separated from the ladder programs, thereby improving productivity, serviceability and security of the programs.

The liquid crystal is written with a laser beam. The laser beam generated by a laser source is applied through an optical control unit such as galvanometer mirrors to the liquid crystal. To erase a part of the data written in the previous time completely, the liquid crystal is irradiated with the laser beam slightly wider than the portion that was thermally written on the liquid crystal in the previous time.

System for partially erasing thermally written liquid crystal element

Brightness of a screen is detected on the basis of a luminous flux projected from a light source to the screen. This detection signal is fed back and a set value of brightness of the screen is compared with the detection signal. The magnitude of input power to the light source is controlled so that the comparison value becomes zero.

Control method of brightness of screen used for projection display and

A counter is provided to count an output pulse which a pulse generator generates each time a vehicle moves by a predetermined distance. A microprocessor is provided to actuate a timer in synchronism with the leading edges of the output pulse from the pulse generator. The timer is set to a constant time interval during which the speed of the vehicle is to be detected. The microprocessor calculates the speed of the vehicle from the count of the counter which count is a value during the time interval from when the timer starts to operate to when the pulse generator generates a pulse just before or after the end point of the set time interval. Thus, the speed of the vehicle can be detected with good resolution and precision.

Speed detecting method and apparatus

A load DC motor is supplied with a DC current through a converter principally consisting of thyristors controlled by an ON-state control signal. The load current is detected both as to the mean value and the variation in time thereof. The mean value of the load current is calculated based on the load current values detected at the time of the present On-signal and the preceding ON-signal. The difference between the reference value and the mean value of the load current is calculated, and the difference between this differential signal and the variation of the load current is further calculated, so that the timing for providing the ON-signal is calculated based on the resultant differential signal.

Growing community of inventors

Hitachi, Japan

Makoto Tachikawa